Petrol engine and intake manifold

ABSTRACT

An intake manifold for a four cylinder internal combustion engine having twin ducts and a twin choke carburettor in which one of the chokes is in communication with two of the cylinders and the other choke is in communication with the other two of the cylinders. The ducts are so arranged that in the normal firing order for the engine the first and third cylinders to fire are connected to one of the chokes and the second and fourth cylinders to fire are connected to the other of said chokes.

United States Patent Bruderlin [45] A r, 2, 1974 [54] PETROL ENGINE AND INTAKE MANIFOLD 457,270 5 1950 Italy 123 52 M [75] Inventor: John Wilfred Bruderlin, Chiswick,

New South wa|es, Australia Primary ExaminerWendell E. Burns Attorney, Agent, or Firm-William A. Knoeller [73] Ass1gnee: Lynx Engineering (Sales) Pty.

Limited, New South Wales, Australia ABSTRACT 22 Filed; Aug 14 2 An intake manifold for a four cylinder internal combustion engine having twin ducts and a twin choke [21 1 Appl' 280,420 carburettor in which one of the chokes is in communication with two of the cylinders and the other choke is 52 us. c1. 123/52 M, 123/59 PC in communication with the other of the cylinders- 51 Int. Cl. F02". 13/04 The duets are $0 arranged the normal firing 53 Field f Search U 123/52 M, 59 PC, 127 order for the engine the first and third cylinders to fire are connected to one of the chokes and the second [56 References Cited and fourth cylinders to tire are connected to the other of said chokes.

1 Claim, 2 Drawing Figures PETROL ENGINE AND INTAKE MANIFOLD This invention relates to intake manifolds for four cylinder petrol engines in which a twin choke carburettor is employed and wherein each cylinder has its own individual inlet port.

With existing intake manifolds for engines of the kind indicated above, the arrangement of the twin choke carburettor outlets, relative to the firing order of the engine cylinders, is such that each of the carburettor chokes feeds cylinders having successive firing order so that of the four firing strokes one carburettor choke feeds fuel forthe first and second of these strokes while the second choke feeds the third and fourth firing strokes. Thus each of the chokes can be regarded as working during two successive firing strokes and then resting during the remaining two firing strokes, our experiments have shown that this type of fuel infeed is appreciably less efficient, so far as engine performance is concerned, than having each choke working for one stroke, resting for the second stroke, working for the third stroke and resting for the fourth stroke.

Consequently, the object of the invention is to provide an intake manifold which will enable operation of an engine in accordance with the sequence system just indicated. With such an arrangement the fuel induction pulses are evenly spaced in point of time by avoiding one choke having to feed two successive firing strokes and this we have found gives higher engine efficiency particularly at low speeds of say, up to 6,000 R.P.M.

The invention provides: In a four cylinder petrol engine having a twin choke carburettor, an intake manifold having ducts whereby one of the chokes is in communication with two of the FIG. 1 is a side elevation of an intake manifold and FIG. 2 is an inverted plan projected from FIG. 1.

The illustrated manifold has a carburettor bolting flange 3 and an engine bolting flange 4. Flange 3 has two inlet ports A and B which register respectively with the twin choke outlets of the carburettor.

The engine flange has four ports in it which respectively open to the four cylinders of the engine. These ports may be conveniently regarded as running from left to right in the drawings and in that direction are designated as 5, 6, 7 and 8. The carburettor and engine flanges of the manifold are joined by ducts such that Port A is connected to Ports 5 and 8 by ducts 9 and 10 and Port B is connected to Ports 6 and 7 by ducts 11 and 12.

Thus, with the usual firing order for a four cylinder engine neither of the carburettor chokes is called upon to supply fuel for successive firing strokes of the engine.

I claim:

1. In a four cylinder internal combustion engine having twin choke side-draft carburettor, a one-piece intake manifold wherein one of the chokes is in communication with two of the cylinders and the other of said chokes is in communication with the other two cylinders, said manifold comprising:

a cylinder bolting flange disposed in a first plane and having first, second,'third and fourth outlet ports co-linearly arranged in said first plane as a row in which said first and fourth outlet ports are the end members of that row,

a choke bolting flange disposed in a second plane substantially parallel to said first plane and having first and second inlet ports therein,

a first main duct through which said first inlet port communicates with said first outlet port,

a first branch duct through which said first main duct communicates with said fourth outlet port,

a second main duct through which said second inlet port communicates with said third outlet port, and

a second branch duct, in crossing relationship with said first branch duct, and through which said second main duct communicates with said second outlet port. 

1. In a four cylinder internal combustion engine having twin choke side-draft carburettor, a one-piece intake manifold wherein one of the chokes is in communication with two of the cylinders and the other of said chokes is in communication with the other two cylinders, said manifold comprising: a cylinder bolting flange disposed in a first plane and having first, second, third and fourth outlet ports co-linearly arranged in said first plane as a row in which said first and fourth outlet ports are the end members of that row, a choke bolting flange disposed in a second plane substantially parallel to said first plane and having first and second inlet ports therein, a first main duct through which said first inlet port communicates with said first outlet port, a first branch duct through which said first main duct communicates with said fourth outlet port, a second main duct through which said second inlet port communicates with said third outlet port, and a second branch duct, in crossing relationship with said first branch duct, and through which said second main duct communicates with said second outlet port. 